This invention relates to racquets for gaming sports such as tennis, squash racquets, racquet ball and badminton. As used in this application, the word racquet comprehends racquets of all types. A racquet has a frame, throat and handle made up as an integral unit of various materials such as wood, graphite fibers, fiberglass, aluminum, steel, boron, titanium, kevlar, polypropylene fibers, polyethylene fibers or combinations of these materials. The frame is strung with string which may be natural gut or synthetic string sometimes referred to as "synthetic gut". The center of gravity of a racquet is at a point along the axis extending between the head and handle of the racquet. This invention relates to the adjustment of the weight and balance of racquets. Particularly, this invention concerns the adjustment of the dynamic balance of a racquet so that it has the desired moment of inertia when it is swept at a ball or shuttlecock in badminton.
Racquets are manufactured with a specified weight within tolerance limits and also with specified center of gravity within tolerance limits. The tolerances are relatively wide so that, as far as the user is concerned, matching of nominally similar racquets with respect to weight and balance is a trial and error process. Users must play test a number of racquets to arrive at the feel of weight and balance and moment of inertia that each prefer.
The playing characteristics of a strung frame of a racquet are dependent on the overall weight, and placement of the weight concentrations along the racquet axes. Personal preferences cover the extremes of the overall weight and weight variations which exist. Most players who develop ball shots that send the ball on long trajectories prefer the balance to be towards the racquet face side; of the midpoint and prefer a heavier overall weight, 350-400 grams. The expression "towards the raquet face side" means away from the handle. Those players who hit the ball on short, high velocity trajectories prefer balance points to the handle side of the midpoint and lighter overall weights, 325-350 grams. Some advanced players prefer to add weight to specific sides of the racquet face to increase the rotational momentum of the racquet through the swing.
The voluminous prior art, spanning between 35 and 45 years, which exists on the adjustment of the weight and balance of racquets (See, for example, Raina U.S. Pat. No. 4,355,803, Col. 1, ln. 30 to Col. 2, ln. 56), demonstrates that this adjustment has been a long-standing problem. This problem has not been satisfactorily solved. In accordance with the current teachings of the prior art there are provided devices for reweighting, rebalancing or increasing the moment of inertia of a racquet which are bulky. In addition, the mounting of these devices on a racquet raises complications. In one case weights are mounted on brackets which are tied to the racquet by straps or strings. The assembly including the bracket, weight and straps would tend to vibrate when a ball is struck causing discomfort and having a tendency to interrupt the concentration of the user. In some cases the weights are installed during manufacture of the racquet. Where such weights are positionally adjustable, such as the members between head and grip disclosed in U.S. Pat. Nos. 2,546,140, 3,912,268, 4,027,881, 4,179,221, the weights would tend to vibrate under the impact of a ball. Where the weights are not positionally adjustable, they can only rarely serve a useful purpose.
It is an object of this invention to overcome the disadvantages and drawbacks of the prior art and to provide weight-and-balance adjusting means or a weight-and-balance adjusting assembly for a racquet which shall be readily integrated into the racquet without requiring brackets or bands and which shall not, when the racquet is in use, cause the racquet to vibrate on impact of a ball. It is also an object of this invention to provide weight-and-balance adjusting means for a racquet which shall afford the user extensive flexibility in readily adJusting the weight and balance.